How has a Christian church been aligned towards the East? Conclusions from statistical analyses of churches built between 300 and 1300

Abstract

Historically nearly nothing has been handed down about the techniques for how a Christian church was built to a certain axis angle. The main aim of the study was to investigate whether church axis angles have been aligned in a west-east direction by either 'astronomical' or 'equinoctial date' orientation. Axis angles of 3014 churches were measured using Internet satellite maps. Multiple regression analyses provided statistical evidence for both astronomical and equinoctial date orientation, whereby probable technical aids (e.g., gnomon, astrolabe) came into use and not direct observations of the sunrise. The left-skewed distribution of church axis angles can be related statistically to an 'Easter window' orientation. However, the statistical analyses also allow for the conclusion that most of the angle orientations of the church axes were rather 'roughly estimated'. No axis angle could be significantly assigned to sunrise angles on a saint's day; however, larger samples are necessary to finally reject this hypothesis. When churches are located on or in Roman masonries, their axis angles often coincide with the orientation angles of the Roman walls, indicating a pragmatically adopted alignment. Taken together, in most cases attempts were made to align churches towards the sunrise at the equinoxes, as requested by the ecclesiastical authorities.

Land- and Skyscapes of the Camino de Santiago: An Astronomy and World Heritage Sustainable Approach

“…However, regional variations appear, perhaps brought about by different methodological approaches or interpretations of the prescription. Ten years after the publication of this work, church orientation continues to attract many researchers from different regions [31][32][33][34][35][36].…”

Ad orientem: Las iglesias románicas del Camino Francés en los reinos de Castilla y León bajo la perspectiva de la Astronomía Cultural

“…Por un lado, se podría conseguir la orientación al este verdadero a partir del estudio de las sombras de un gnomon, como expone Vitruvio en su De architectura (LI.VI.6). Sin embargo, también existe la idea de orientar al sol por medio de la observación directa de su salida en determinados momentos del año (Kräuchi 2021). En concreto, se puede constatar la existencia de al menos tres opciones en este sentido: hacia el equinoccio, ya sea este considerado el 21 o el 25 de marzo; hacia la salida del sol en la fecha del santo patrón; o hacia la fecha de la Pascua en el año de construcción.…”